Transaction Firewall Method and System

2. The method of claim 1, wherein the applying one or more predefined rules to each of the respective fields to determine whether the transaction is fraudulent further comprises calculating a transaction score.

3. The method of claim 2, wherein the transaction is determined to be fraudulent when the transaction score exceeds a predetermined threshold.

4. The method of claim 1, wherein the decoding each transaction message into respective fields is performed using a decode table.

5. The method of claim 1, further comprising sending a response message to an originating system of the transaction indicating whether the transaction has been blocked, denied, or rate limited.

6. The method of claim 1, wherein at least one of the one or more predetermined rules is determined using a machine learning engine or algorithms at the server.

7. The method of claim 1, wherein the transaction is selectively blocked, denied, or rate limited at the transaction firewall upon instruction received from the server.

8. The method of claim 1, wherein the server includes the transaction firewall.

9. The method of claim 1, wherein the transaction firewall is communicatively coupled to the server over the network.

10. The method of claim 1, wherein the transaction is a financial transaction.

11. The method of claim 1, wherein the systems of the payment environment include one or more of an acquiring device, a terminal handler, a transaction switch, and an authorization host.

12. The method of claim 1, wherein the transaction firewall is configured as a policy enforcement point and the server is configured as a policy decision point.

13. The method of claim 1, wherein the respective fields include transaction message payload fields.

14. The method of claim 13, wherein content of the transaction message payload fields includes shared primary account number (“PAN”) information.

15. The method of claim 1, wherein the content of the one or more specified fields does not include Internet Protocol (“IP”) address or port number information.

16. The method of claim 1, wherein the method is performed in real-time.

19. The method of claim 18, wherein, using a processor at the server, the server: correlates the respective transaction messages for each leg of the transaction journey into an end-to-end model of the transaction, the correlating based on content of the respective fields; applies one or more predefined rules to the content of each of the respective fields to determine whether the transaction is fraudulent; when the transaction is determined to be fraudulent, determines the one or more specified fields of the respective fields to use to selectively block, deny, or rate limit the transaction; selects the corresponding predefined rule from a server rule base; and, sends the predefined rule to the transaction firewall.

22. The method of claim 21, wherein, using a processor at the transaction firewall, the transaction firewall: receives packets of the transaction from the network; reconstructs and frames the packets from the each leg into the respective transaction messages in accordance with respective transaction message formats; decodes each transaction message into its respective fields; sends the each transaction messages and its respective fields to the server; receives the predefined rule and stores the predefined rule in a transaction firewall rule base; applies the predefined rule to the transaction to selectively block, deny, or rate limit the transaction based on content of the one or more specified fields in the transaction; and, when the transaction is determined not to be fraudulent, that is, when the transaction firewall rule base does not include an applicable predefined rule, bridges the transaction through the transaction firewall and into the payment environment.